Manufacturing Nuclear Weapon “Pits”: A Decisionmaking Approach for Congress

Summary

A “pit” is the plutonium “trigger” of a thermonuclear weapon. During the Cold War, the Rocky Flats Plant (CO) made up to 2,000 pits per year (ppy), but ceased operations in 1989. Since then, the Department of Energy (DOE) has made at most 11 ppy for the stockpile, yet the Department of Defense stated that it needs DOE to have a capacity of 50 to 80 ppy to extend the life of certain weapons and for other purposes. This report focuses on 80 ppy, the upper end of this range.

Various options might reach 80 ppy. Successfully establishing pit manufacturing will require, among other things, enough laboratory space and “Material At Risk” (MAR). MAR is essentially the amount of radioactive material permitted in a building that could be released in an accident; there must be enough MAR available for manufacturing within the MAR “ceiling.” PF-4, the main plutonium building at Los Alamos National Laboratory (LANL), or other structures would house manufacturing. Analytical chemistry (AC), which analyzes the composition of samples from each pit to support manufacturing, will also require availability of MAR and space.

For an option to support 80 ppy, MAR and space available for manufacturing and AC must exceed MAR and space required for 80 ppy. “Margin” is the amount by which an available amount exceeds a required amount. This report presents amounts of MAR and space potentially available for manufacturing under several options, though they may require updating. Calculation of margin—needed to determine if an option passes a minimum test for feasibility—also requires data on MAR and space required for 80 ppy, yet these data have never been calculated rigorously. As a result, it is not known if an option would increase capacity too little (making an option infeasible), too much (making an option too costly), or by an appropriate amount. Congress could direct the National Nuclear Security Administration, which operates the nuclear weapons program, to provide data on space and MAR required to manufacture 80 ppy. These data would permit calculation of space margin and MAR margin as static numbers. However, the situation is dynamic: uncertainties may materialize over time, increasing or decreasing margin.

AC poses different issues. It is needed to support production. It requires much space but uses little MAR. The nuclear weapons complex has ample excess space and MAR available for AC, so margin is not at issue, though such factors as logistics might become an issue.

Thus, three key decisions face Congress in deciding how to produce 80 ppy:

Decision 1: For pit manufacturing, is there currently enough margin for space and MAR in PF-4? If not, what can be done to provide it?

Decision 2: Once enough margin for space and margin for MAR are provided for pit manufacturing, what steps can be taken to maintain these margins over decades in the face of uncertainties?

Decision 3: How much AC should be done at LANL, what is needed to make the space and MAR at LANL sufficient to support that amount of AC, and how much, if any, AC should be done at other sites?

Choosing among options also requires data on how options compare on cost and other metrics, setting up a process for downselection.

This report is best viewed in color, as it contains many multicolored graphics.